Wemos mini and OLED shield bitcoin ticker

In this example we will display the price in USD of 1 bitcoin, the data is taken from coindesk’s API and displayed on an oled display.

This is similar to our previous examples, you do not need to use a Wemos mini or the OLED shield below but this makes the project easier to build

Here is the oled shield for the Wemos mini

Here is the wemos mini

Code

#include <ESP8266WiFi.h>
#include <Wire.h>
#include <SFE_MicroOLED.h>
#include <ArduinoJson.h>

const char* ssid = "iainhendry";
const char* pass = "iain061271";
#define PIN_RESET 255 //
#define DC_JUMPER 0 // I2C Addres: 0 - 0x3C, 1 - 0x3D
String id;
String value;
String json;

MicroOLED oled(PIN_RESET, DC_JUMPER); // I2C Example

WiFiClient client;

// delay between updates
const unsigned long postingInterval = 60L * 1000L;
unsigned long lastConnectionTime = 0;

void setup()
{
delay(100);
Serial.begin(115200);
Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, pass);
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());

Serial.print("Connecting to ");

oled.begin();
oled.clear(ALL);
oled.setCursor(0,0);
oled.display();
oled.clear(PAGE);
oled.clear(ALL);
oled.print("Bitcoin price");
oled.setCursor(0,1);
oled.print("loading..");
oled.display(); // Display what's in the buffer (splashscreen)
delay(50);

}

int check_connect = 0;

void httpRequest()
{
client.stop();

// if there's a successful connection:
if (client.connect("api.coindesk.com", 80))
{
Serial.println("connecting...");
client.println("GET /v1/bpi/currentprice.json HTTP/1.1");
client.println("Host: api.coindesk.com");
client.println("User-Agent: ESP8266/1.1");
client.println("Connection: close");
client.println();
lastConnectionTime = millis();
}
else
{
// if you couldn't make a connection:
Serial.println("connection failed");
}
}

void loop()
{
int cnt;

if (cnt++ == 10000)
{
cnt = 0;
if (check_connect++ == 50)
{
check_connect = 0;
if (WiFi.status() != WL_CONNECTED)
{
}
}
}

if (millis() - lastConnectionTime > postingInterval)
{
httpRequest();
unsigned int i = 0; //timeout counter
int n = 1; // char counter
char json[500] ="{";

while (!client.find("\"USD\":{")){}

while (i<20000)
{
if (client.available())
{
char c = client.read();
json[n]=c;
if (c=='}') break;
n++;
i=0;
}
i++;
}

StaticJsonBuffer<500> jsonBuffer;
JsonObject& root = jsonBuffer.parseObject(json);

String newjson = root["code"];
String value = root["rate"];
id = newjson.substring(9,12);

// value = newjson.substring(41,51);
oled.display();
oled.clear(PAGE); // Clear the display's internal memory
oled.clear(ALL); // Clear the library's display buffer
oled.setCursor(0,1);
oled.print(value);
oled.display();

id="";
value="";
}
}

testing

You should see something like this on the oled display

Links

Here are some of the products I used

Smart Electronics D1 mini – Mini NodeMcu 4M bytes Lua WIFI Internet of Things development board based ESP8266 by WeMos

0.66″ inch For Wemos Oled 64X48 IIC I2C LCD OLED LED Dispaly Shield for Arduino Compatible For WeMos D1 Mini SSD1306 OLED Shield

by hotcoin.net